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    Electronic Structure Study of Ni-B Alloy Coatings by XAFS Technique
    (Springer, 2021) Özkendir, Osman Murat; Cengız, Erhan; Karahan, Ismail Hakki; Klysubun, Wantana
    The crystal and electronic structure properties of Ni-B (nickel-boron) alloy coatings produced by an electrodeposition method have been investigated. The crystal structures of the alloy coatings were determined by x-ray diffraction patterns and supported by extended x-ray absorption fine structure (EXAFS) spectroscopy. The local atomic structure around the Ni atom was obtained from EXAFS studies at the Ni K-edge, and the EXAFS data were fitted with theoretical calculations. With the addition of boron atoms in the nickel environment, NiB composite alloys were formed in the crystals with an orthorhombic "Cmcm" structure. The analysis revealed a limited effect of boron doping in the electronic structure of the nickel atoms. Boron atoms were determined as sitting between the Ni atoms and causing a disturbance in the crystal structure due to providing inhomogeneous interstitial potential and defects. © 2021, The Minerals, Metals & Materials Society.
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    Exploring the structural and electronic properties of CeO2 thin films: role of thickness, temperature, and oxygen vacancies
    (National Institute of Optoelectronics, 2025) Günaydın, Selen; Cengız, Erhan; Kanmaz, İmran; Apaydın, Gökhan; Miyazaki, Hidetoshi; Harfouche, M.; Özkendir, Osman Murat
    Systematic investigation of the temperature-dependent local arrangements in CeO2 thin films and their direct impact on electronic properties is presented. Results revealed that thicker films promote oxygen vacancy formation, reducing Ce4+ to Ce3+ and modifying the local coordination. Furthermore, temperature-dependent EXAFS analysis uncovers a local structural rearrangement transition above 400 K, driven by thermal activation of oxygen vacancies. This rearrangement, occurring within a globally stable cubic framework, directly alters the hybridization between Ce 4f/5d and O 2p orbitals. Density Functional Theory (DFT) calculations corroborate the experimental findings, revealing an indirect bandgap of 1.60 eV as a result of orbital hybridization. © 2025, National Institute of Optoelectronics. All rights reserved.